Xylose-modified phenol-formaldehyde resins

Xylose Modified Phenol-Formaldehyde Resins. Xylose (I) and byproducts streams containing xylose (e.g., wood prehydrolysates from the production of chemical pulps and waste liquors from the wet process for hardboard production) are readily available. Our previous experiments (2) showed that free reducing sugars are not acceptable modifiers for phenol-formaldehyde resins cured under basic conditions. 

Figure 4. Variation of the dry- and wet- (hatched) wood failures of modified phenol-formaldehyde resins. The moles of modifier were varied as indicated. The mole ratio of phenol to formaldehyde was 1 2.3. The wood failures of xylose- and prehydrolysate-modified resins were similar and were averaged.

Phenol-formaldehyde resins modified directly with reducing sugars successfully bond wood veneers at neutral conditions. The dry- and wet-shear strengths of two-ply panels bonded with xylose-modified resins are not adversely affected until the amount of xylose is increased to between 0.6 and 1.0 moles xylose per mole of phenol (Figure 2). However, even resin with 2 moles xylose per mole of... 

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